1. Technical Field
This invention relates to control systems for electrically heated, cold weather garments, and more particularly to an electronic control system and method for controlling the ambient temperature within an electrically heated, cold weather garment.
2. Discussion
Electrically heated garments, or portions thereof, are helpful in combatting the effects of cold temperatures on a person subject to prolonged exposure to the cold. More specifically, a heated garment can prove helpful to persons such as sportsmen, farmers, construction workers, public officials, military personnel, etc. who frequently are exposed to cold weather for prolonged periods of time.
Problems with prior art electronic control systems for heated garments have existed with respect to the ability to heat a plurality of discrete zones of the garment independently. Heating different zones individually is desirable because of the varying rate at which different parts of the body lose heat. The extremities (i.e., hands, feet and head), for example, suffer a greater heat loss than the torso. In addition, physical activities of the wearer of the garment can cause different body parts of the wearer to generate heat at varying levels. A system which applies the same level of heat to all areas of the garment can therefore produce a temperatures in at least some of the zones within the garment that is uncomfortable to the wearer.
Prior art electronic control systems, to be able to sense and control the heat applied to various zones of the garment independently, typically require a heat sensing means, for example, a thermistor, located within each particular area of the garment to be sensed. Examples of systems that require, or would appear to require, a plurality of temperature sensing and/or selection devices for independently controlling various discrete heating elements of a garment are disclosed in the following U.S. patents:
______________________________________ U.S. Pat No. Issued Inventor(s) ______________________________________ 710,429 1902 Collins et al 2,579,383 1951 Goudsmit 3,084,241 1963 Carrona 3,293,405 1966 Costanzo 3,648,745 1972 Starr 3,648,764 1972 Starr ______________________________________
Such systems also typically require a temperature selection device, for example, a thermostat, for controlling the temperature of a particular area of the garment.
The need for multiple, discrete temperature sensors and selection devices complicates the temperature control circuit and adds to the cost of the system, while detracting from the overall reliability of the system. Systems requiring a plurality of such elements further detract from the convenience to the wearer, who may have to periodically readjust numerous temperature selection devices as weather conditions or physical activities of the wearer change.
It is therefore a principal object of the present invention to provide an electronic temperature control system for controlling the temperature of a plurality of predetermined zones of a cold weather garment independently of each other.
It is further an object of the present invention to provide a temperature control system and a method capable of automatically regulating the ambient temperature within each zone of the garment independently of the other zones.
It is yet another object of the present invention to provide a control system which accomplishes this automatic control of temperature in each zone without the need for a discrete temperature sensing device to be disposed within each zone of the garment.
It is still a further object of the present invention to provide a temperature control system capable of rapidly increasing or decreasing the temperature within each zone independently of the other zones.
It is another objective of the present invention to provide a temperature control system operable to maintain a plurality of independent areas of the garment at the same temperature in response to an input from a single temperature selection device, thereby promoting the convenient use of the system.